I've had to stop and ditch veggies as well at the northern CA borders; fair enough - CA grows a large percent of the countries food and pests are a serious economic issue for growers.
Here is WA state, I have been pulled over to have my kayak inspected for millfoil (water weed) that is clogging waterways. It's an invasive species and is causing millions of dollars in damage.
Canada has some similar provisions at the border... My band did a tour there a few years ago and one of my band mates had a bag of apples in the car at the border. She was so offended at the demand to hand them over for disposal, that she refused and we pulled over while she ate all 5 apples in the sack. This was a horrible idea btw.... it torqued off the border guards who took the opportunity to search the car and more horribly had some substantial digestive repercussions a couple of hours down the road...